Per screenshots of since-deleted tweets, per @harrisonmc15, Durant's account responded with a third-person reply blaming head coach Billy Donovan and a lackluster roster beyond him and Russell Westbrook.
The poster hypothesized that Durant meant to defend himself using a different account. It's also possible someone on his social media staff thought they were tweeting from a personal page. Or someone fabricated the retorts as a joke that developed a life of its own.
Have no fear, for Reddit detectives are on the case. As laid out by SB Nation's Tim Cato, forum users uncovered what appears to be Durant's private Instagram account.
Why is any of this relevant? Cato also showed that account arguing in the comments section of posts related to Durant. [Warning: NSFW]
Durant intentionally blasting Donovan and a Thunder team that "was just him and Russ" on a public platform in the third person seems like the least plausible explanation.